I think Github tarballs are fine.
Tags with REL${version} are going to be the release tags.
To trigger toolchain usage (and disable enforcer at the same time),
you need to use `mvn package -Prelease` command.
However, it might be better to create -Pactivate-toolchains to make
that explicit.
Sample toolchains.xml file can be found in the source root of pgjdbc project.
You might want to add -DskipTests, otherwise you need to have a
running PostgreSQL instance to execute the tests.
Vladimir